1. Technical Field
The present disclosure relates to a remote node, a center node, a communication system, a communication terminal, a communication method, and a program. In particular, the present disclosure relates to a remote node, a center node, a communication system, a communication terminal, a communication method, and a program for performing mobile communication.
2. Background Art
Currently, a base station used in a radio communication system includes a baseband process unit that collectively performs processes in a Layer-1 process part and a Layer-2 process part. Processes related to a physical layer are performed in the Layer-1 process part and processes for controlling the physical layer are performed in the Layer-2 process part.
Meanwhile, as the number of antennas and the width of a system radio frequency band will increase in radio communication systems in the future, application of a C-RAN (Centralized Radio Access Network) structure in which the Layer-1 process part and the Layer-2 process part are separated from each other has been studied. For example, 3GPP TR 38.801 V0.2.0 (2016-06) (hereinafter referred to as “Non-patent Literature 1”) discloses the C-RAN structure. In Non-patent Literature 1, the Layer-1 process part is described as a “Distributed Unit” or “Lower layers of NR (New Radio) BS (Base Station)” and the Layer-2 process part is described as a “Central Unit” or an “Upper Layer of NR BS”. Non-patent Literature 1 discloses a configuration in which a plurality of Distributed Units connect to one Central Unit.
Further, Non-patent Literature 1 also discloses an example of a function distribution between the Central Unit and the Distributed Unit. For example, Non-patent Literature 1 mentions that a function that is executed in a MAC (Medium Access Control) layer, such as an HARQ (Hybrid Automatic Repeat Request), is installed in the Distributed Unit. By installing the function related to the HARQ in the Distributed Unit as described above, a signal transmission between the Distributed Unit and the Central Unit in a resending process is omitted and hence an increase in the resending process time can be prevented.